U.S. voters more likely to support marijuana legalization than non-voters

Much has been made of a recent Gallup poll showing a majority of Americans now support marijuana legalization. But if a majority support legalization, why do politicians seem so reluctant to support drug law reform?

One explanation for this puzzle is that Americans who vote are less likely to support legalization than those who do not vote. Voters tend to be older, and possibly have other characteristics which are associated with opposition to drug policy reform.

The Gallup poll result is consistent with, but shows somewhat more support than, recent results from the General Social Survey (GSS), which suggest that roughly half of Americans supported legalization in 2011 and 2012. Unlike the Gallup polls, the GSS data are available to researchers, and include a wide variety of information on respondents, including whether or not they voted in the most recent Presidential election.

I set out to show using all GSS waves between 1975 and 2012 which include the legalization support question (n=26,870) that people who vote are less likely to support legalization than people who do not vote, which would help explain why politicians seem out of sync with public sentiment.

But I found the opposite.

The graph shows support for legalization for all respondents, for respondents who voted in the last Presidential election, and for respondents who did not vote in the last election. Up until about a decade ago, voters tended to be moderately less likely to support legalization than non-voters. But since 2004 voters have been modestly more likely to support legalization than non-voters. Restricting attention to post 2004 sample waves, voters are 3.8 percentage points more likely support than non-voters (z=2.61).

So the puzzle is not resolved by differences in attitudes towards legalization across voters and non-voters.

Correlates of support for legalization.

I also ran a few regressions to check if what we see in the graph goes away with a few basic controls (notably age), and how support varies with demographic characteristics. The table below shows results from regression models in which the dependent variable is a dummy indicating support for legalization. Each cell contains the estimated parameter with the associated t-ratio below. The covariate of interest is “voted last elec.”, a dummy indicating the respondent voted in the preceding Presidential election. (All estimates are marginal effects from probit regressions with robust standard errors.)

The first column shows that, over the entire sample from 1975 through 2012, voting in the last election is associated with about three percentage points lower support for legalization (z=4.59). The second column adds complete sets of age and year dummies, which are enough to flip the sign on the voter dummy. Holding age constant and removing any common trend over time in voting propensities and support for legalization, U.S. voters are slightly more likely to support legalization than non-voters (by 1.4 percentage points, z=2.49). The results on the age effects (unreported) suggest that all else equal older cohorts are less likely to support than younger cohorts, providing some sketchy evidence in favor of the notion that support will increase over time as older cohorts, er, shrug this mortal coil.

The model presented in the last column adds controls for religion, education, political leanings, and region, which does essentially nothing to the estimated association between voting and support for legalization.

The results also show that religious belief and behavior are strong predictors of support: non-religious people are substantially more likely to support legalization than otherwise identical non-religious people (by about 17 percentage points, z=13.71), observant religious people are much less likely to support than religious but non-observant people (by about 14 percentage points, z=14.15).

The omitted education category is high school dropouts. More education strongly predicts higher support for legalization, other things equal.

Finally, holding all else equal, people with moderate political leanings (the omitted category) are more likely to support than conservatives (by about 6 percentage points, z=7.85) and less likely to support than liberals (by about 11 percentage points, z=13.68).